CAREER: Jet Measurements and a Novel Hadronic Calorimeter at the Relativistic Heavy Ion Collider

该奖项支持PI和她的研究小组在调查中了解强核力，并与亚特兰大地区的中学生和高中生接触，以扩大他们对核物理的理解。夸克和胶子是正常物质最基本的组成部分。然而，由于核力的作用，它们不能被单独观察到，而被限制在原子核中的质子和中子等粒子中。在极端的温度和密度下，一种被称为夸克-胶子等离子体（QGP）的物质的新状态可以形成。QGP是强作用力理论的一个很好的试验台。相对论重离子对撞机（RHIC）是世界上能够产生QGP的两个设备之一。除了产生QGP外，重离子碰撞还会产生高能夸克和胶子，它们与QGP相互作用，然后产生一种称为“射流”的粒子喷雾，可以用探测器测量。虽然之前的RHIC实验已经显示了射流能量损失的证据，但一项名为sPHENIX的新实验将能够精确测量完全重建的射流。sPHENIX包括一个特殊的探测器，这是RHIC的第一个中心强子量热计（HCal），对于测量这些喷流的能量至关重要。除了与喷流相关的分析外，该合同还包括在组装前用宇宙射线测试HCal组件，并为这种新型探测器开发校准程序。与sPHENIX HCal合作将为GSU的不同本科生提供机会，以获得研究和硬件方面的经验。参与该项目的本科生和研究生将接受大数据分析、大型合作网络和开发有用的硬件技能的培训，这些技能对于在各种STEM领域培养下一代都很重要。使用类似于sPHENIX HCal的组件，GSU学生将与亚特兰大地区的中学生和高中生一起测量宇宙射线。GSU女性物理学学生组织的参与（PI是该组织的顾问）允许初高中学生在学生选择职业道路的关键时刻从事科学工作，并与不同的科学家群体一起工作，旨在帮助鼓励不同的人群追求STEM职业。sPHENIX强子量热计具有新颖的倾斜板设计，其中包括嵌入在钢板之间的闪烁瓦。该合同包括为这种新型探测器开发校准程序，这将是成功测量的关键。用宇宙射线测试闪烁体块将提供基线校准信息，而来自光束测试原型的经验将有助于开发校准程序，最终可能包括在p+p碰撞中使用光子标记射流来设置射流能量尺度。光子标记射流也是QGP的重要探针。由于光子未被QGP修改，光子的能量提供了获得相反射流初始部分能量的途径，因此可以获得损失了多少能量。在准备PHENIX的同时，该项目将根据PHENIX 16年的数据进行最精确的光子标记相关测量。这些相关测量涉及到传输系数q帽，它测量每单位路径长度的部分的能量损失。射流结构测量可以进一步了解介质中粒子的破碎和能量损失。sPHENIX将在RHIC上实现新的射流观测，这将促进我们对QGP能量损失机制的理解，从而进一步加深我们对极端条件下QCD的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award supports the PI and her research group in investigations to understand the strong nuclear force and to engage with middle and high school students in the Atlanta area to broaden their understanding of nuclear physics. Quarks and gluons are the most fundamental building blocks of normal matter. However, due to the nuclear strong force, they cannot be observed individually and are confined within particles like protons and neutrons in the nucleus. Under extreme temperatures and densities, a new state of matter known as the quark-gluon plasma (QGP) can be formed. The QGP is an excellent test bed for the theory of the strong force. The Relativistic Heavy Ion Collider (RHIC) is one of two facilities world-wide capable of creating the QGP. In addition to producing the QGP, heavy ion collisions produce energetic quarks and gluons that interact with the QGP and then produce a spray of particles called a "jet" that can be measured with detectors. While previous RHIC experiments have shown evidence of jet energy loss, a new experiment called sPHENIX will enable precise measurements of fully reconstructed jets. sPHENIX includes a special detector, the first central hadronic calorimeter (HCal) at RHIC, which is essential for measuring the energy of these jets. In addition to jet related analyses, this award includes testing HCal components with cosmic rays before assembly and development of a calibration procedure for this novel detector.Working with the sPHENIX HCal will provide opportunities for the diverse population of undergraduates at GSU to gain experience in research and hardware. The undergraduate and graduate students involved in this project will be trained to work in big data analysis, network within large collaborations and develop useful hardware skills that are all important for preparing the next generation in a variety of STEM fields. Using components similar to those for the sPHENIX HCal, GSU students will work with Atlanta area middle and high school students to measure cosmic rays. Participation of the GSU Women in Physics student organization, for which the PI is the advisor, allows the middle and high school students to engage in science and work with a diverse group of scientists at a critical time when students are choosing career paths and is intended to help encourage a diverse population to pursue STEM careers. The sPHENIX hadronic calorimeter has a novel tilted plate design, which includes scintillator tiles embedded between steel plates. This award includes the development of a calibration procedure for this novel detector, which will be essential for successful measurements. Testing the scintillator tiles with cosmic rays will provide baseline calibration information and experience from the beam test prototype will be useful in developing the calibration procedure, which ultimately may include using photon tagged jets in p+p collisions to set the jet energy scale. Photon tagged jets are also important probes of the QGP. Since the photon is unmodified by the QGP, the photon's energy provides access to the initial parton energy of the opposing jet and therefore access to how much energy was lost. In parallel to sPHENIX preparations, this project will make the most precise photon tagged correlation measurements achievable from the 16 years of PHENIX data. These correlation measurements access the transport coefficient, q-hat, which measures the energy loss of partons per unit pathlength. Jet structure measurements give further insight to the fragmentation and energy loss of the partons in the medium. sPHENIX will enable new jet observables at RHIC that will advance our understanding of energy loss mechanisms in the QGP and thereby further our understanding of QCD under extreme conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.